> Until that new compiler, IBM pretty much entirely ignored ANSI PL/I,> which is semantically very incompatible with IBM's original definition> of the language.

I would like to see some indication of how IBM PL/I was "very
incompatible" with the ANSI version given that the ANSI spec was
derived from IBM's internal spec for the language.
[The ANSI standard is phenomenally hard to read because of all of the
formalisms. I wouldn't be surprised if some of the differences were
due to misunderstandings about what all the formal goop actually
meant. -John]